The present invention relates generally to a fuel injector. More specifically, the present invention relates to the coil assembly for a fuel injector of an internal combustion engine.
Fuel injectors are generally defined as an electromagnetic valve mechanism that sprays fuel into the intake system of an internal combustion engine.
Proper control of the moving portion of a fuel injector improves fuel spray quality while limiting flow rate variation. This moving portion, or guiding valve, opens and closes to allow fuel to pass uniformly through an opening of the injector valve seat. In a fuel injector, the controlling of the guiding valve is based on the generation of energy via a coil assembly.
The coil assembly is a multi-functional device that provides structure to wind wires, structure to support electrical interface elements, structure to capture interface terminals during insertion and termination, and is the energy source that is utilized to generate a magnetic field to open the injector valve.
The coil assembly is comprised of five major pieces. These pieces are a bobbin, two terminals, wire, and a bobbin clip. The terminals are attached to the bobbin through the two terminal posts located on a portion of the bobbin. The wire is wrapped around the winding bay of the bobbin and each end of the wire is wrapped around a portion of a different terminal and secured to the terminal typically by soldering. The portion of the terminals containing the wire is then secured within the framework of the bobbin by attaching a bobbin clip to the bobbin. The other end of the terminals is then available to be connected to a power source. The coil assembly is then placed within a fuel injector. When a current is introduced to the terminals through the power source, the wire creates a magnetic field which causes the coil assembly to energize, which in turn causes the guiding valve to open and allow fuel to pass through an opening in the injector valve seat.
A shortcoming of presently available coil assemblies is the inaccuracies of the method of mechanically pressing the terminals through the bobbin terminal posts because the terminals may bend or may be positioned incorrectly, causing the assembly to be non-useable. Another drawback to known processes is that a clip is added to the assembly to insure that the portion of the terminals containing the wire are fully rotated and secured into the framework of the bobbin. This clip may cause interference in the future assembly if the clip is not attached correctly. Also, this clip has a tendency to become unattached or lost if the clip is not attached correctly. The additional costs associated with re-application of the clip, lost time in failed assemblies due to the loss of the clip, or bent or inaccurately located terminals increase the cost of the injector on a per-vehicle basis.
It is, therefore, one object of the present invention to provide a fuel injector, for use in an internal combustion engine, having a simple and precise means of centering and securing the terminals in the coil assembly of a fuel injector. A feature of the present invention is to provide the coil assembly with open terminal posts that provide an entrance for the terminals via a translational push. The open terminal posts are configured such that the terminals are held in place securely yet allowed to rotate. To allow the terminals to be positioned properly, a pair of flange holding notches have been added to the bobbin as well. The open terminal posts and the flange holding notches allow the terminals to be more accurately positioned for height and depth, and thus the secured terminals are more readily available to receive a length of wire that is soldered to the terminals.
An additional feature of the present invention is to provide flange-locking notches that capture the terminals when rotated. This locking feature removes the need for bobbin clips that are used to make sure the terminals are correctly rotated and secured. Part quantity reduction and scrap reduction due to bobbin clip breakage are an advantageous by-product of the elimination of the bobbin clip. Further, there is no longer a need to have an operator to install the bobbin clip, thus further improving the throughput for assembling the bobbin.
Other features and advantages of the present invention will become apparent from the following detailed description that should be read in conjunction with the accompanying drawings.